Pet fountain filter



FIG. 1 is a bottom, front and left side perspective view of a pet fountain filter, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a rear elevational view thereof; and,

FIG. 7 is a front elevational view thereof. 

CLAIM The ornamental design for a pet fountain filter, substantially as shown and described. 